Reproductive biology of a mycoheterotrophic species, Burmannia wallichii (Burmanniaceae)

Abstract

The breeding system of a mycoheterotrophic species, Burmannia wallichii (Miers) Hook. f. (Burmanniaceae), is assessed using field observations, floral anatomy, pollen histochemistry and isozyme electrophoresis. The structure of the flower effectively prevents pollinators from accessing the stamens, and no pollinators were observed visiting natural populations in Hong Kong. The pollen is starch-rich but lipid-poor. Analysis of isozyme variation revealed a small proportion of polymorphic loci, a low level of total heterozygosity (H(T) = 0.1972), and a very high overall fixation index of populations (F(IT))= 0.6602). These results strongly suggest that B. wallichii is predominantly self-pollinated. The coefficient of gene differentiation (G(ST)) is low (0.05), although it is suggested that this is due to genetic homogenization of populations consonant with the formation of numerous tiny 'diaspora' seeds that are wind dispersed. (C) 2000 The Linnean Society of London.